search

AOMediaCodec / av1-rtp-spec

Current draft (HTML): https://aomediacodec.github.io/av1-rtp-spec/
Other
63 stars 24 forks source link

clarification re Dependency Descriptor #229

Closed zhuker closed 10 months ago

zhuker commented 3 years ago

4.3 Dependency Descriptor RTP Header Extension To facilitate the work of selectively forwarding portions of a scalable video bitstream, as is done by a Selective Forwarding Middlebox (SFM), certain information needs to be provided for each packet. Appendix A of this specification defines how this information is communicated.

Can the DD extension be omitted in absence of SFM or scalable video? If so do you think it should be clarified?

murillo128 commented 3 years ago

This is the actual behaviour of chrome implementation AFAIK. DD is only used when scalability modes are configured and not sent when scalability is not used.

Also, being a header extension and it has to be negotiated on the SDP by both endpoints, so any of them could decide to not enable it.

Not sure if it requires a modification on the draft though as the usage of the DD is not mandatory by the spec even in case that a SFM is in use.

zhuker commented 3 years ago

Thanks for the clarification Shouldn't it say what you just said?

On Thu, Jul 1, 2021, 22:21 Sergio Garcia Murillo @.***> wrote:

This is the actual behaviour of chrome implementation AFAIK. DD is only used when scalability modes are configured and not sent when scalability is not used.

Also, being a header extension and it has to be negotiated on the SDP by both endpoints, so any of them could decide to not enable it.

Not sure if it requires a modification on the draft though as the usage of the DD is not mandatory by the spec even in case that a SFM is in use.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/AOMediaCodec/av1-rtp-spec/issues/229#issuecomment-872492604, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABBKKQXB6VU7FLSNWBYEFBDTVS54XANCNFSM47VITDAA .

aboba commented 10 months ago

RTP header extensions (including negotiation) are defined in RFC 8285, which is cited as a normative reference. So there is no need to repeat text from RFC 8285 in this specification.